| /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
| |
| #include <errno.h> |
| #include <fcntl.h> |
| #include <stdint.h> |
| #include <stdlib.h> |
| #include <sys/time.h> |
| #include <sys/xattr.h> |
| |
| #include "alloc-util.h" |
| #include "errno-util.h" |
| #include "fd-util.h" |
| #include "macro.h" |
| #include "missing_syscall.h" |
| #include "sparse-endian.h" |
| #include "stat-util.h" |
| #include "stdio-util.h" |
| #include "string-util.h" |
| #include "time-util.h" |
| #include "xattr-util.h" |
| |
| int getxattr_at_malloc( |
| int fd, |
| const char *path, |
| const char *name, |
| int flags, |
| char **ret) { |
| |
| _cleanup_close_ int opened_fd = -EBADF; |
| unsigned n_attempts = 7; |
| bool by_procfs = false; |
| size_t l = 100; |
| |
| assert(fd >= 0 || fd == AT_FDCWD); |
| assert(name); |
| assert((flags & ~(AT_SYMLINK_FOLLOW|AT_EMPTY_PATH)) == 0); |
| assert(ret); |
| |
| /* So, this is single function that does what getxattr()/lgetxattr()/fgetxattr() does, but in one go, |
| * and with additional bells and whistles. Specifically: |
| * |
| * 1. This works on O_PATH fds (which fgetxattr() does not) |
| * 2. Provides full openat()-style semantics, i.e. by-fd, by-path and combination thereof |
| * 3. As extension to openat()-style semantics implies AT_EMPTY_PATH if path is NULL. |
| * 4. Does a malloc() loop, automatically sizing the allocation |
| * 5. NUL-terminates the returned buffer (for safety) |
| */ |
| |
| if (!path) /* If path is NULL, imply AT_EMPTY_PATH. – But if it's "", don't — for safety reasons. */ |
| flags |= AT_EMPTY_PATH; |
| |
| if (isempty(path)) { |
| if (!FLAGS_SET(flags, AT_EMPTY_PATH)) |
| return -EINVAL; |
| |
| if (fd == AT_FDCWD) /* Both unspecified? Then operate on current working directory */ |
| path = "."; |
| else |
| path = NULL; |
| |
| } else if (fd != AT_FDCWD) { |
| |
| /* If both have been specified, then we go via O_PATH */ |
| opened_fd = openat(fd, path, O_PATH|O_CLOEXEC|(FLAGS_SET(flags, AT_SYMLINK_FOLLOW) ? 0 : O_NOFOLLOW)); |
| if (opened_fd < 0) |
| return -errno; |
| |
| fd = opened_fd; |
| path = NULL; |
| by_procfs = true; /* fgetxattr() is not going to work, go via /proc/ link right-away */ |
| } |
| |
| for (;;) { |
| _cleanup_free_ char *v = NULL; |
| ssize_t n; |
| |
| if (n_attempts == 0) /* If someone is racing against us, give up eventually */ |
| return -EBUSY; |
| n_attempts--; |
| |
| v = new0(char, l+1); |
| if (!v) |
| return -ENOMEM; |
| |
| l = MALLOC_ELEMENTSOF(v) - 1; |
| |
| if (path) |
| n = FLAGS_SET(flags, AT_SYMLINK_FOLLOW) ? getxattr(path, name, v, l) : lgetxattr(path, name, v, l); |
| else |
| n = by_procfs ? getxattr(FORMAT_PROC_FD_PATH(fd), name, v, l) : fgetxattr(fd, name, v, l); |
| if (n < 0) { |
| if (errno == EBADF) { |
| if (by_procfs || path) |
| return -EBADF; |
| |
| by_procfs = true; /* Might be an O_PATH fd, try again via /proc/ link */ |
| continue; |
| } |
| |
| if (errno != ERANGE) |
| return -errno; |
| } else { |
| v[n] = 0; /* NUL terminate */ |
| *ret = TAKE_PTR(v); |
| return (int) n; |
| } |
| |
| if (path) |
| n = FLAGS_SET(flags, AT_SYMLINK_FOLLOW) ? getxattr(path, name, NULL, 0) : lgetxattr(path, name, NULL, 0); |
| else |
| n = by_procfs ? getxattr(FORMAT_PROC_FD_PATH(fd), name, NULL, 0) : fgetxattr(fd, name, NULL, 0); |
| if (n < 0) |
| return -errno; |
| if (n > INT_MAX) /* We couldn't return this as 'int' anymore */ |
| return -E2BIG; |
| |
| l = (size_t) n; |
| } |
| } |
| |
| static int parse_crtime(le64_t le, usec_t *usec) { |
| uint64_t u; |
| |
| assert(usec); |
| |
| u = le64toh(le); |
| if (IN_SET(u, 0, UINT64_MAX)) |
| return -EIO; |
| |
| *usec = (usec_t) u; |
| return 0; |
| } |
| |
| int fd_getcrtime_at( |
| int fd, |
| const char *path, |
| int flags, |
| usec_t *ret) { |
| |
| _cleanup_free_ le64_t *le = NULL; |
| STRUCT_STATX_DEFINE(sx); |
| usec_t a, b; |
| int r; |
| |
| assert(fd >= 0 || fd == AT_FDCWD); |
| assert((flags & ~(AT_SYMLINK_FOLLOW|AT_EMPTY_PATH)) == 0); |
| assert(ret); |
| |
| if (!path) |
| flags |= AT_EMPTY_PATH; |
| |
| /* So here's the deal: the creation/birth time (crtime/btime) of a file is a relatively newly supported concept |
| * on Linux (or more strictly speaking: a concept that only recently got supported in the API, it was |
| * implemented on various file systems on the lower level since a while, but never was accessible). However, we |
| * needed a concept like that for vaccuuming algorithms and such, hence we emulated it via a user xattr for a |
| * long time. Starting with Linux 4.11 there's statx() which exposes the timestamp to userspace for the first |
| * time, where it is available. Thius function will read it, but it tries to keep some compatibility with older |
| * systems: we try to read both the crtime/btime and the xattr, and then use whatever is older. After all the |
| * concept is useful for determining how "old" a file really is, and hence using the older of the two makes |
| * most sense. */ |
| |
| if (statx(fd, strempty(path), |
| (flags & ~AT_SYMLINK_FOLLOW)|(FLAGS_SET(flags, AT_SYMLINK_FOLLOW) ? 0 : AT_SYMLINK_NOFOLLOW)|AT_STATX_DONT_SYNC, |
| STATX_BTIME, |
| &sx) >= 0 && |
| (sx.stx_mask & STATX_BTIME) && |
| sx.stx_btime.tv_sec != 0) |
| a = (usec_t) sx.stx_btime.tv_sec * USEC_PER_SEC + |
| (usec_t) sx.stx_btime.tv_nsec / NSEC_PER_USEC; |
| else |
| a = USEC_INFINITY; |
| |
| r = getxattr_at_malloc(fd, path, "user.crtime_usec", flags, (char**) &le); |
| if (r >= 0) { |
| if (r != sizeof(*le)) |
| r = -EIO; |
| else |
| r = parse_crtime(*le, &b); |
| } |
| if (r < 0) { |
| if (a != USEC_INFINITY) { |
| *ret = a; |
| return 0; |
| } |
| |
| return r; |
| } |
| |
| if (a != USEC_INFINITY) |
| *ret = MIN(a, b); |
| else |
| *ret = b; |
| |
| return 0; |
| } |
| |
| int fd_setcrtime(int fd, usec_t usec) { |
| le64_t le; |
| |
| assert(fd >= 0); |
| |
| if (!timestamp_is_set(usec)) |
| usec = now(CLOCK_REALTIME); |
| |
| le = htole64((uint64_t) usec); |
| return RET_NERRNO(fsetxattr(fd, "user.crtime_usec", &le, sizeof(le), 0)); |
| } |
| |
| int listxattr_at_malloc( |
| int fd, |
| const char *path, |
| int flags, |
| char **ret) { |
| |
| _cleanup_close_ int opened_fd = -EBADF; |
| bool by_procfs = false; |
| unsigned n_attempts = 7; |
| size_t l = 100; |
| |
| assert(fd >= 0 || fd == AT_FDCWD); |
| assert((flags & ~(AT_SYMLINK_FOLLOW|AT_EMPTY_PATH)) == 0); |
| assert(ret); |
| |
| /* This is to listxattr()/llistattr()/flistattr() what getxattr_at_malloc() is to getxattr()/… */ |
| |
| if (!path) /* If path is NULL, imply AT_EMPTY_PATH. – But if it's "", don't. */ |
| flags |= AT_EMPTY_PATH; |
| |
| if (isempty(path)) { |
| if (!FLAGS_SET(flags, AT_EMPTY_PATH)) |
| return -EINVAL; |
| |
| if (fd == AT_FDCWD) /* Both unspecified? Then operate on current working directory */ |
| path = "."; |
| else |
| path = NULL; |
| |
| } else if (fd != AT_FDCWD) { |
| /* If both have been specified, then we go via O_PATH */ |
| opened_fd = openat(fd, path, O_PATH|O_CLOEXEC|(FLAGS_SET(flags, AT_SYMLINK_FOLLOW) ? 0 : O_NOFOLLOW)); |
| if (opened_fd < 0) |
| return -errno; |
| |
| fd = opened_fd; |
| path = NULL; |
| by_procfs = true; |
| } |
| |
| for (;;) { |
| _cleanup_free_ char *v = NULL; |
| ssize_t n; |
| |
| if (n_attempts == 0) /* If someone is racing against us, give up eventually */ |
| return -EBUSY; |
| n_attempts--; |
| |
| v = new(char, l+1); |
| if (!v) |
| return -ENOMEM; |
| |
| l = MALLOC_ELEMENTSOF(v) - 1; |
| |
| if (path) |
| n = FLAGS_SET(flags, AT_SYMLINK_FOLLOW) ? listxattr(path, v, l) : llistxattr(path, v, l); |
| else |
| n = by_procfs ? listxattr(FORMAT_PROC_FD_PATH(fd), v, l) : flistxattr(fd, v, l); |
| if (n < 0) { |
| if (errno == EBADF) { |
| if (by_procfs || path) |
| return -EBADF; |
| |
| by_procfs = true; /* Might be an O_PATH fd, try again via /proc/ link */ |
| continue; |
| } |
| |
| if (errno != ERANGE) |
| return -errno; |
| } else { |
| v[n] = 0; /* NUL terminate */ |
| *ret = TAKE_PTR(v); |
| return (int) n; |
| } |
| |
| if (path) |
| n = FLAGS_SET(flags, AT_SYMLINK_FOLLOW) ? listxattr(path, NULL, 0) : llistxattr(path, NULL, 0); |
| else |
| n = by_procfs ? listxattr(FORMAT_PROC_FD_PATH(fd), NULL, 0) : flistxattr(fd, NULL, 0); |
| if (n < 0) |
| return -errno; |
| if (n > INT_MAX) /* We couldn't return this as 'int' anymore */ |
| return -E2BIG; |
| |
| l = (size_t) n; |
| } |
| } |
